Recording capacity of magnetic hard disc drives is increasing at a high annual rate. In order to achieve satisfactory recording system performance, high linear and track densities are required. In order to attain high linear and track densities, especially high linear density, magnetic material that is deposited onto a surface of a recording medium of the magnetic disc drive is manufactured in increasingly smaller diameters. Very small particles of magnetic material can become magnetically unstable in the presence of thermal agitation. The minimum size of a magnetic particle is limited by the effect of thermal energy surrounding the particle. The effect of the thermal energy reduces, or eliminates, the ability of a magnetic particle to hold a charge. This effect is referred to as the super-paramagnetic effect. The limit for a magnetic particle to hold a charge is referred to as the super-paramagnetic limit.
The super-paramagnetic effect is detrimental to the reliability of a magnetic hard disc drive, and the integrity of the data stored on the magnetic hard disc drive. Magnetic material affected by the super-paramagnetic effect becomes unstable and loses its magnetic state. An unstable and/or lost magnetic state is undesirable because information is stored in magnetic hard disc drives in the form of magnetic states. Losing these magnetic states is equivalent to losing data.
The super-paramagnetic effect is characterized by the rate of degradation of signal amplitude. One rate of degradation follows a sinusoid analog signal, such as a constant “2T pattern.” Constant 2T patterns are well known to those skilled in the art. The rate of degradation is also called thermal decay measurement.
The thermal decay measurement of magnetic disc drive devices is tested during design prototyping to determine the quality and/or reliability of the device. To test a prototype device during a design phase of a magnetic disc drive, firmware that certifies a design is downloaded to a read-only-memory (ROM) of the prototype magnetic disc drive device, and the design certification firmware is executed. The design certification firmware includes a number of certifying tests. During the design certification process, the design certification tests are executed on a magnetic disc drive device in a predetermined sequence of the tests until the entire sequence of certifying tests is completed or halted. The sequence of certifying tests will halt when any one of the tests in the sequence fails.
One of the certifying tests is a test of the bit error rate (BER) of the magnetic disc drive device. The BER is an indication of the quality and/or reliability of the device during certifying a design for acceptance or failure rejection. The BER is also used for tuning a read channel of the magnetic disc drive device. However, BER determination is a slow process that increases the cost of certifying a design and tuning a magnetic disc drive device. Moreover, is it difficult to correlate the amplitude degradation rate of the signal to a bit error rate (BER). The BER is an important specification for magnetic disc drives.
One conventional method of determining the BER when certifying a design of a magnetic disc drive device includes determining the time-domain equalized signal-to-noise ratio (ESNR). The time-domain ESNR of a magnetic disc drive device is closely correlated with the BER of the magnetic disc drive device. The time-domain ESNR is determined by computer-readable logic that is implemented outside of the magnetic disc drive device. The time-domain ESNR test logic is not stored on, or downloaded to memory of the magnetic disc drive device. In one example, the logic is implemented in software on a host computer that is operably coupled to the magnetic disc drive device through a communication channel or link. The logic is executed after retrieving the respective data from the magnetic disc drive device. However, the communication channel or link between the device that implements the time-domain ESNR logic and the magnetic disc drive device is slow. The slow link has the effect of delaying transfer of magnetic disc drive data that is input to the time-domain ESNR logic.
Furthermore, in conventional systems, user data stored on a magnetic disc drive device is difficult to reconstruct or repair when errors are introduced to the user data. User data is difficult to reconstruct because user data appears to be random with no regular pattern, and is reflected as a random analog signal. In contrast to a constant sinusoid analog signal that characterizes the Super-paramagnetic effect.
A conventional method of performing time-domain equalized signal-to-noise ratio (ESNR) calculation includes over-sampling an analog read-back signal. The analog read-back signal is received from a magnetic disc drive device with a high speed digital storage oscilloscope (DSO). The over-sampled digital data is received by a software read channel. The software read channel is a signal processing program that is external to the magnetic disc drive device. The software read channel synchronizes the disc drive with the DSO for measurement of the time-domain ESNR. The software read channel simulates the operation of a physical read channel up to a stage of input to a Viterbi Detector, which is primarily equalization. The equalized signal is then resampled at the input to the viterbi detector for statistical analysis to determine the time-domain ESNR. However, the simulation of the operation of the physical read channel by the software read channel is less accurate than actual operation of the physical read channel. In addition, preparation for measuring the amplitude degradation rate of a magnetic disc drive is also cumbersome in conventional systems. This conventional method is tedious and requires extensive external software processing and additional equipment, such as the DSO Furthermore, the read channel of conventional mass storage devices includes the ability to redirect digital samples to a non-return-to-zero (NRZ) bus. A NRZ bus is transmits data in digital binary form, whereby each positively or negatively charged data bit is separated from its predecessor and successor by time rather than a neutral charge.
Sample signals from a read head of the mass storage medium are converted from analog to digital by an analog to digital converter (ADC). FIG. 10 illustrates a conventional analog signal of read data from a mass storage medium.
However, the ADC operates much faster than the NRZ bus, in some examples, approximately eight times faster. Thus, only one phase of read data can be output to the NRZ bus for every eight phases of read data. FIG. 11 illustrates conventional sampling of one of every eight phases of an analog signal of read data.
In FIG. 11, one out of every eight phases is sampled, indicated by the dots along the analog signal. Sampling one out of every eight phases does not allow a comprehensive analysis of the behavior of the mass storage device.
What is needed is a system, method and/or apparatus that provides a reliable test of a design prototype of a magnetic disc drive device. In addition, a system, method and/or apparatus that provides sampling of all phases of read signals from a mass storage medium of a mass storage device is needed.
The present invention provides a solution to this and other problems, and offers other advantages over the prior art.